Abstract
Hot-mix asphalts exposed to hot weather and high traffic volumes can display rutting distress. A material that can be used to increase the stiffness of asphalt binders is gilsonite. On the other hand, from an environmental point of view, the virgin natural aggregates of asphalt mixtures can be replaced with recycled concrete aggregates. For these reasons, this study modified the asphalt binder with gilsonite by wet-process to improve rutting resistance, and replaced (by mass and volume) part of the coarse fraction of the aggregate with recycled concrete aggregate in two hot-mix asphalts with different gradations. Unlike other studies, a larger experimental phase was used here. Marshall, indirect tensile strength, resilient modulus, permanent deformation, fatigue resistance, and Cantabro tests were performed. An ANOVA test was carried out. If the replacement of the virgin aggregate by recycled concrete aggregates was made by volume, both materials (gilsonite and recycled concrete aggregate) could be used in hot-mix asphalts for thick-asphalt layers in high temperature climates and any level of traffic. The use of both materials in hot-mix asphalts is not recommended for thin-asphalt layers in low temperatures climates. It is not advisable to replace the aggregates by mass.
Highlights
Given all of the above reasons, in contrast to other studies conducted on the topic, this study evaluated the combined effects of modifying asphalt cement (AC) with gilsonite through a wet process, and replaced part of the coarse fraction of natural origin aggregates (NA) with recycled concrete aggregates (RCAs) in mixes of MDC-19 and MDC-25
On the other hand, when the replacement of the NA with RCA was carried out according to mass, the mixes that utilized modified asphalt tended to slightly increase the resilient modulus (RM); said increases were not statistically significant according to the ANOVA test
The replacement of NA with RCA according to volume helped to increase resistance to the phenomenon of rutting even more so, which was coherent with the increase of RM in these mixes
Summary
Gilsonite is a natural fossil resource that was discovered more than one century ago, it has been broadly studied It is a type of natural asphalt (generally solid) derived from petroleum, which has a predominantly dark brown color, and is found widely around the world. It is naturally produced through the penetration of oil or petroleum in rocks under combined actions of heat, pressure, oxidation, and microbe activity throughout millions of years [1]. It is a hard and brittle material [2], but it can be crushed into powder. In comparison with other modifiers, gilsonite offers advantages in terms of lower costs and increased ease of use [1,5,21,24,32,39]
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